package com.lvxh.exp.filter.global;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Image extends HttpServlet
{

    /**
     * TODO 添加字段注释
     */
    private static final long serialVersionUID = -4215977145812482996L;

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     * 
     * @param request
     *            servlet request
     * @param response
     *            servlet response
     */
    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException
    {
        response.setContentType("image/jpeg");
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        HttpSession session = request.getSession();
        // 在内存中创建图象
        int width = 60, height = 20;
        BufferedImage image = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);

        // 获取图形上下文
        Graphics g = image.getGraphics();

        // 生成随机类
        Random random = new Random();

        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);

        // 设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));

        // 画边框
        // g.setColor(new Color());
        // g.drawRect(0,0,width-1,height-1);

        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 155; i++)
        {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }

        // 取随机产生的认证码(4位数字)
        String sRand = "";
        for (int i = 0; i < 4; i++)
        {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110), 20 + random
                    .nextInt(110), 20 + random.nextInt(110)));// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.drawString(rand, 13 * i + 6, 16);
        }

        // 将认证码存入SESSION
        session.setAttribute("rand", sRand);
        // 图象生效
        g.dispose();
        ServletOutputStream responseOutputStream = response.getOutputStream();
        // 输出图象到页面
        ImageIO.write(image, "JPEG", responseOutputStream);

        // 以下关闭输入流！
        responseOutputStream.flush();
        responseOutputStream.close();
    }

    Color getRandColor(int fc, int bc)
    {// 给定范围获得随机颜色
        Random random = new Random();
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }

    // <editor-fold defaultstate="collapsed"
    // desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     * 
     * @param request
     *            servlet request
     * @param response
     *            servlet response
     */
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException
    {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     * 
     * @param request
     *            servlet request
     * @param response
     *            servlet response
     */
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException
    {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     */
    public String getServletInfo()
    {
        return "Short description";
    }
    // </editor-fold>
}